This application proposes to study fundamental aspects of transcription and chromatin regulation, using the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. Our studies will focus on several areas that are conserved with higher eukaryotes. First, we will study the regulation of cryptic promoters spread throughout the genome, with the goal of understanding their mechanism of activation and their possible biological significance. These promoters have the potential to express novel genetic information. As they are known to be regulated, at least in part, by conserved eukaryotic factors, they likely exist in other eukaryotes. Second, we will study Spt6, an essential factor in yeast that also plays significant roles in mammalian cells. Our experiments will use affinity purification and microarray experiments to address how Spt6 controls chromatin structure, define its interactions with other proteins, and understand itslocalization across the genome. Third, we will address how cells control the level of the most abundant chromatin proteins, histones. Our previous work identified a previously unknown mechanism for histone gene amplification. By genetic and molecular approaches, we plan to understand the mechanism of this amplification and the gene products that regulate its frequency. Fourth, as another approach to understand the regulation of histone levels, we will study SptIO and Spt21, factors that control histone gene transcripton in vivo. We will use genome-wide localization analysis to identify their sites of chromatin association and affinity purification to identify the proteins with which they interact. Finally, we will continue a new project to elucidate the functions of nucleosome remodeling complexes in the fission yeast, S. pombe. Our work to date has shown that the S. pombe Swi/Snf and RSC complexes differ significantly from those of S. cerevisiae. Our future work will use genetic and molecular approaches to understand the roles of actin- related proteins in S. pombe, which are only required under particular growth conditions. In addition, we will follow up on our observation that many of the genes controlled by Swi/Snf are in large clusters. Yeasts are outstanding model systems for understanding disease-related aspects of human cells. Spt6, Swi/Snf, and chromatin structure in general have all been strongly implicated in cancers and other diseases. Our studies should help to understand these disease states in humans.